Damaged needle detection apparatus

ABSTRACT

A detection and control apparatus for a knitting machine having a coil through the field of which the machine needles pass and a pair of coupled oscillators operating in frequency step with the phase change due to a broken needle passing through the coil detected to control stopping the machine.

United States Patent 1191 1111 3,910,074

Parker I1 Oct. 7, 1975 DAMAGED NEEDLE DETECTION 3,588,686 6/1971 Lingmann 324/41 APPARATUS 3,646,542 2/1972 Anthony [76] I Ed d I P k 34 O k R d 3,690,127 9/1972 Tellerman et al 66/157 nventor: war ar er, a 1 go Road, Holden, Mass. 01520 OTHER PUBLICATIONS Beeler, C., Finding Buried Stuff In Radio-Electronics,

[21] Appl. No.: 360,636

Primary Examiner-W. C. Reynolds Assistant Examiner-Andrew M. Falik [52] US. Cl. 66/157; 324/41; 324/82 At 1 h l [51 Int. c1. D04B 35/18 tomeyAgen" C ares Pfund [58] Field of Search 66/157, 163, 16355433116872, [57] ABSTRACT A detection and control apparatus for a knitting ma- [56] References Cited cEine havicrillg g coil thrgugh the field of \lavlcliich till? itna- 0 me nee es pass an a pair 0 coup e osc1 a ors UNITED STATES PATENTS operating in frequency step with the phase change due to a broken needle passing through the coil detected OO 3,397,364 8/1968 crandan to control stopping the machme. 3,492,564 1/1970 Baker 324/41 6 Claims, 6 Drawing Figures 20 /7 I8 4 II" US. Patent Oct. 7,1975 Sheet 1 of 3 3,910,074

miw

w d "'1' I l i Q DAMAGED NEEDLE DETECTION APPARATUS CROSS REFERENCE TO RELATED APPLICATIONS 'This-application is related to applicants' copending application Ser. No. 359,857, filed May 14, 1973, now US. Pat. No. 3,854,084, issuing Dec. 10,1974, and Ser. No. 447,965, filed Mar. 4, 1974.

I BACKGROUND OF THE INVENTION In the operation of a conventional textile machine such as a knitting machine or the like, a considerable problem is presented because'of the fact that the machine uses a large number of delicate needles operating at high speed. The probability of an individual needle breaking is quite high and, when a needle is broken, it introduces a flaw into thefabric. Because the operating area of the machine is necessarily rather inaccessible, the flaw is not noticed until the fabric begins to emerge from the knitting area and this may be some time later. This means that, not only is it necessary to discard or sell cheaply a substantial part of the knitted fabric,-but a substantial portion of the operaitng time of the knitting operating has been used before it is discovered that it is producing inferior fabric. Since the machines represent a substantial capital investment, non-productive time represents the loss of a portion of the capital investment, so the net cost of sealable fabric is higher.

'Attempts have been made in the past to detect broken needles and to shut down the machine when one occurs. However, such attempts have ended in failure v because of the high expense of adequate equipment to perform the operation and because the means of doing.

so have been complicated. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.

It is, therefore, an outstanding object of the invention to provide a detecting apparatus for a textile machine or the like which is sensitive in operation, so that it can detect a small change in the shape of a needle.

Another object of this invention is the provision of a detecting apparatus for a textile machine such as a knit-. ting machine, which apparatus can be applied to existing machines without substantial modification thereof.

A further object of the present invention is the provision of a detecting means for a machine, which means has no mechanical parts to interfere with the knitting operation.

It is another object of the instant invention to provide a detecting apparatus for use in detecting a broken needle in a knitting machine or the like which apparatus is simple in construction, relatively inexpensive to manufacture, and which is capable of a long life of useful service with a minimum of maintenance.

A still further object of the invention is the provision of a detecting apparatus for a knitting machine or the 7 SUMMARY OF THE INVENTION In general, the invention has to do with a detecting apparatus for use in detecting a defective needle in a knitting machine. The apparatus is provided with a first More specifically, the test coil is in the form of an elongated loop having a narrow slot-like opening through which a plurality of needles pass.

BRIEF DESCRIPTION OF THE DRAWINGS The character of the invention, however, may be best understood by reference to one of its structural forms, as illustrated by the accompanying drawings, in which:

FIG. 1 is a perspective view of a knitting machine'incorporating a detecting apparatus according to the principles of the present invention,

FIG. 2 is an enlarged perspective view of a portion of the knitting machine showing certain details of the detecting apparatus, l

FIG. 3 is an electrical schematic view of a power rack forming part of the detecting apparatus, r i FIG. 4 is an electrical schematicview of the main electronic circuitry of the detector apparatus, and I FIG. 5 is an electrical schematic view of a relay operating portion of the detecting apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG; 1, wherein are best shown the general features of the invention, the detecting ap'paratus, indicated generally by the reference numeral '10, is shown in use on a knitting machine 1 1. For the purpose of illustration, the knitting machine is shown as being of the circular type for producing a tube of knitted fab- 40 .ric 12. The knitting machine has a frame 13 on which the detecting apparatus 10 is mounted in proximity to the operating elements of the machine on the interior of the frame. Mounted at the top of the frame are bobbins 14, carrying the raw yarn that is to be guided into the apparatus toform the fabric. Also mounted on the frame is a controlcabinet 15 which contains the electrical equipment for controlling the speed of operation of the machine, as well as the .usual switches for shutting off the machine.

In FIG. 2 a portion of the detecting apparatus 10 is shown with its cover removed. The annular test coil 16 is provided with leads l7 and 18 and is mounted adjacent the path of the knitting needles 19. The test coil is in the form of an elongated annulus with a narrow slot-like opening 21 extending through it.

A horizontal section through. the coil is shown in FIG. 2a. It can be seen that the needles 19 extend in a horizontal row outwardly from the knitting machine and at a certain portion of the knitting machine periphery the needles are moved outwardly by an internal cam (not shown). This cam causes the row of needles to bulge out in a curved envelope 22. The coil is located so that this envelope resides inside of the opening 21 in the coil 16, thus effecting the inductance of the coil in an amount determined by the amount of steel in the needles lying within the envelope. In FIG. 2a, one of the needles 23 is shown as broken, which interrupts the envelope and reduces the integrated value of the steel FIGS. 3, 4, and show the electronic circuits associatedvwith the coil 16. FIG. 4 shows the main detectingcircuit, while FIG. 3 shows the power pack which provides it with suitable electricity and FIG. sv shows the manner in which thedetecting equipment is used to opcrate suitable relays toterminate the knitting machine operation. In FIG. 3 the power pack is shown as hav ing two input lines 24 and 25, as well as an interrupt switch 26. The lines 24 and 25 are connected to an 11,0-volt source of alternating current of electricity. The otheremds of the lines 24 and 25 are connected to the opposite. ends. of the primary coil 28 of a transfor rneij27. Across the primary coil is a 0.01 microfarad capacitor used to by-pass voltage surges. The transformer 27 has a reduction ratio of 110/24 volts AC.. One end of thesecondary coil 29 is connected to ground, theother end of the secondary coil is connected by a line 32. The other end of the line 32 is connected tothe ends of two 47ohm resistors 33 and 34,

tor 44 to ground. The line 37 is also connected through a 047K ohrn resistor 45 to a 8 line 46. The resistors,

41 45 are connected;respectively, through 9-volt Zenordiodes 47 and 48 to ground.

Referring now to FIG. 4, which shows the details of the detectoir circuit 50, it can be seen that it incorporates the test coil 16, as well as a reference coil 5. The

testcoil 16 is incorporated in a first oscillating circuit 52, while the reference coil 51 is incorporated 51. a second oscillating circuit 53. The coupling 54 is connected between the first and second oscillating circuits, the couplingconsisting of a 68K ohm resistor 55. The

oscillator circuits are connected to a control circuit 56,

which compares singals frornthe oscillators and terminates the machine operation in the case of imbalance.

Actually, the control circuit drives relays 57, operates a meter 58, and also operates automatic phase control 59. Note that the lines 43 and 46 of the power pack 20 are connected to respective B 71- and B terminals of thev detector circuit 50. Incorporated in the detector circuit are a number of transistors 63 through 76, all transistors being of the 2N 3415 type.

The line 61 is connected to a 22K ohm resistor 77 and to one end of an 82 millihenry inductance 78. The other end of the inductance 78 is connected to a line 79. A 5 microfarad capacitor 80 is connected between the line 79 and the junction between the resistor 77 and the base of the transistor 63. A variable inductance 81 a connects line 79 to the collector of the transistor 63.

Line 79,is connected to ground through a 0.05 .microfarad capacitor82. The collector of the transistor is also connected to a line 83 andthe test coil 16 has one end connected to the line 79 and the other end connected to the line 83. A line 84 extends from the line 83 to the horizontal plates of the oscilloscope. The

emitter of the transistor 63 is connected through a 1K ohm resistor 85 to ground, and it is also connected to ground through a 5 microfarad capacitor 86. The line 83 is connected to ground through a 0.0 1 microfarad capacitor 87.

The line 62 is connected through a 22K ohm resistor 88 to the base of the transistor 64.'It is also connected to one side ofan 82 millihenry inductance 89, the other end of which is connected via line 91 to a 5 microfarad capacitor. 92- the other terminal of which is connected to the base of the transistor 64. The reference coil 51 is connected on one end to the line 91 and at the other endto the collector of the transistor 64. The line 91 also is connected to ground through a 0.05 microfarad capacitor 93. The collector of the transistor 64 is connected to a line 94, which is connected to ground through a 0.01 microfarad capacitor 95. The emitter of the transistor 64 is connected through a 1K ohm resistor 96 to'ground and also through a 5 microfarad capacitor 97 to ground. A line 98 is connected to the line 94 and extends to the vertical plates of the cathode ray oscilloscope.

Connected between the output-lines 83 and 94 of the oscillators are these elements in series, including a 100 picofarad capacitor 99, a 10 to 60 picofarad signal controlledcapacitor which changes with applied voltage, e.g., 100, and a 47ohm resistor 101. The line 94 is also connected to ground through a variable capacitor 102, capable of adjustment from 3 to'6O picofarads for initial adjustments. A switch 103 connected on one side to a point between .thecapacitor 99 and the varactor 100, and on the other side to the automatic phase'control 59 is used to shut off the APC for preliminary adjustment of the oscillators. The output lines 83 and 94 of the oscillators are connected to the input points of a bridge rectifier 104 of the IN-34 type. The output points of the rectifier are connected to lines 105 and 106. The line 105 is connected through a 4.7 megohm resistor 107 to thebase of the transistor 69, whose emitter is connected through a 22K ohm resistor 108 to ground. The collector is connected to B 1. The emitter of the transistor 69 is connected through a one megohm resistor 109 to the base of the transistor 71. The emitter of the transistor 71 is connected through a 100K ohm resistor 1 10 to ground. The collector of that transistor 71 is connected to B l by a 100k ohm resistor and through a l megohm resistor 111 to the'base of the transistor 72. The emittter of the transistor 72 is connected to the. ground through a 22K ohm resistor 112 and the emitter is also-connected to a line 113.

The line 106, which it will be remembered, is connected to one of the output points of the rectifier 104 is connected through a 4.7 megohm resistor 114 to the base of the transistor 70, whose emitter is connected through a 22K ohm resistor 115 to ground and whose collector is connected to 3 1. The emitter of the transistor 70 is connected through a line'l 16 to the emitter of the transistor 71.

The line 113 is connected through a 4.7 megohm resistor 117. to the base of the transistor 65, whose emitter is connected to ground through a 100K ohm variable tap resistor 118 and whose collector is connected to 8 1. The movable tap of the resistance 1 18 is connected through a 150K ohm resistor 119 to the base of the transistor 66. The transistor 66 has its emitter connected through a lk'ohm resistor 120 to ground. The collector of the transistor 66 is connected to 8 1 by a 100K resistor and to the base of theitransistor 67, whose collector is connected through a 3.9 ohm resistor 121 to the line 46 of the power pack which carries the B; voltage. The emitter of the transistor 67 is connected through a ohm resistor 122 to ground. It is also connected to the emitter of the transistor 68. The collector of the transistor 67 is connected to the base of the transistor 68, while the collector of the transistor 68 is connected through the coil of the relays 57 to 8 voltage on the line 46 of the power pack. The line 1 13 is also connected through the transistors 73 and 74 to operate the meter 58. More specifically, it is connected through a 4.7 megohm resistor 123 to the base of the transistor 73, whose emitter is connected through a 100K ohm variable resistor 124 to ground and whose collector is connected to B l. The movable tap of the resistor 124 is connected through a 220K ohm resistor 125 to the base of the transistor 74.

The emitter of the transistor 74 is connected through a 1K ohm resistor 126 to ground. Its collector is connected to one side of the meter 58, which meter is capable of reading from O to 100 micro-amps and then through a 10K resistor to B l.

The line 1 13 is also connected to the automatic phase control circuit through the transistors 75 and 76. More specifically, it is connected through a 4.7 megohm resistor 127 to the base of the transistor 75, whose emitter is connected through a 100K ohm variable resistor 128 to ground and whose collector is connected to B l. The movable tap of the resistor 128 is connected through a one megohm resistor 129 to the base of the transistor 76, and also to a5 microfarad capacitor 130 to ground. The emitter of the transistor 76 is connected through a 1k ohm resistor 131 to ground, while its collector is connected through a 100K ohm resistor to B l, a 5 microfarad capacitor 133 to ground, and a 100K ohm resistor 132 to the automatic phase control 59.

FIG. 5 shows the arrangement of the relays 57. The point A, is of course, connected to the collector of the transistor 68 in FIG. 4. It is connected to one side of relay coils 134 and 135, the other side of which is connected through 270 ohm resistors 136 and 137 to the 8 voltage line 46 of the power pack. The coil 134 0perates on contactors 138 which are connected through switches 139 and 140 to ground. Coil 135 operates output contactors 141, which operate in the control cabinet of the knitting machine to shut down the machine. With both switches 139 and 140 closed, when relays operate they remain in closed position until reset switch 139 is opened. Switch 140 is opened for adjustment only.

The operation of the invention will now be readily understood in view of the above description. The knitting machine 11 is set in motion by operating certain controls on the control cabinet 15. Yarns from the bobbins 14 are led down through the machine and operated on by the needles 19, these needles being moved radially by cams on the interior of the machine. The needles knit the yarn from the bobbins 14 to form the fabric 12. As the knitting takes place, the needles in the area of the coil 16 bulge outwardly to form the envelope 22. When a broken needle 23 enters the envelope. the coil 16 has its inductance changed and this changes the output phase of the first oscillating circuit 52. The signal appearing on the output lines 83 and 84 is then out of phase with the signal from the second oscillating circuit 53 which appears on the line 94 and the line 98, so that the figure which appears on the cathode ray os cilloscope becomes distorted. The imbalance phase on the lines 83 and 94 also enters the control circuit 56 and demonstrates itself in various ways there. The imbalance appears on the meter 58 and it also serves to operate the relays 57 to shut down the knitting machine as hereinafter described with reference to FIG. 5. During normal operation the test coil 16, senses good needles and along with the variable inductance 81, operates the first oscillating circuit 52 at the same frequency as the second oscillating circuit 53 and with a pre-set phase angle difference having a first value which can be considered a nominal phase relation. This nominal phase relation can be maintained by an auto matic phase control signal feedback at 59 which enters the varactor circuit joining the lines 83 and 94 through the switch 103. The: resistor 55 being a linear impedance operates as a part of the coupling 54 which transfers oscillatory energy bidirectionally to maintain the oscillator 52 and the oscillator 53 in frequency. It is only when a sufficient predetermined imbalance ap pears in the test coil 16 that the pre-set phase angle changes enough to operate the relays. The capacitor 133 delays the changing of APC voltage and thus does not follow the abrupt phase change caused by a broken needle.

It can be seen then, that by use of the present apparatus one obtains a very sensitive control of the knitting machine or other needle textile machines. This is true despite the high-speed operation of the machine and the fact that the needles 19 pass very rapidly through the slot 21 in the coil 16, because the apparatus is sensitive enough to shut down the machine when a broken needle appears in the envelope 22. As it can be seen, the present apparatus is very compact and does not interfere with the normal operation of the knitting machines without difficulty.

It is obvious that minor changes may be made in the form and construction of the invention without departing from the material spirit thereof. It is not, however, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope claimed.

The invention having been thus described, what is claimed as new and desired to secure by Letters Patent 1. In combination with a knitting machine having a plurality of knitting needles arranged around the pen'phery of said machine and adapted to move in a peripheral path about the machine frame during the knitting operation with means at a predetermined location in said path for projecting said needles to expose the hooked end thereof as they move in sequence past said location,

a first oscillating circuit having a frequency determining tuned circuit for producing oscillatory energy at the oscillating frequency,

a test coil at said location coupled to said tuned circuit for producing an inductive field at said oscillating frequency through which a plurality of said needles sequentially moves as they are projected at said location to enter, be exposed to and exit the field of said test coil during operation of said machine,

a second oscillating circuit nominally operating at substantially the same frequency as said first oscillating circuit,

a coupling for bidirectional transfer of oscillatory energy between said first and second oscillating circuits, said coupling maintaining said oscillating circuits in frequency step,

means for setting a nominal phase relation between the oscillations of said first and second oscillating circuits when said plurality of needles of normal configuration are in said field of said test coil for producing a control signal having a first value which changes in response to changes in said nominal phase relation, and

means responsive to predetermined change in said control signal resulting from the phase change produced by one of said plurality of needles having an inductance altering abnormal configuration in said field of said test coil for stopping operation of said machine.

2. Detection apparatus as recited in claim 1, wherein the test coil is in the form of an elongated loop having a slot-like center opening into which the needles pass.

3. Detection apparatus as recited in claim 2, wherein the needles normally pass in a row around the machine frame, but extend from the row at a certain location to form a protruding envelope, the test coil being mounted at the said location, so that the envelope resides in the center opening of the test coil.

4. Apparatus according to claim 1 and including signal controlled capacitance circuit means interconnecting said oscillating circuits, an automatic phase control signal circuit responsive to detected phase difference between said oscillating circuits to produce an automatic phase control signal and means for coupling said automatic phase control signal to said signal controlled capacitance means to control said first and second oscillating circuits.

5. Apparatus according to claim 4 including switch means for selectively applying said phase control signal.

6. The method of controlling a knitting machine to stop operation upon detection of a broken needle occurring in a uniform sequence of needles comprising the steps of,

operating two similar oscillators tuned to approximately the same frequency with the frequency determining elements of one of said oscillators influenced by a predetermined pattern of a plurality of knitting needles as they normally appear during operation of said machine,

moving all of the needles of the machine through said pattern in sequence relative to said frequency determining elements,

coupling oscillatory energy between said oscillators to lock them in frequency step with predetermined phase for said predetermined pattern,

detecting the phase between said oscillators to respond to on broken needle in said pattern, and controlling operation of said machine to stop upon detection of one broken needle in said pattern.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,910,074 DATED October 7, 1975 v 0 (5) Edward I. Parker It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 23, "operaitng" should be operating line 28, "sealable" should be saleable Column 2, line 24, "rack" should be pack Column 3, line 39, "5" should be 51 lines 41 and 42, after "incorporated" delete "51" and insert in Column 4, line 24, "these" should be three line 27, before "100" insert varactor same line, "47" should be 47K Column 5, line 2, "3.9" should be 3.9K

Signed and Scaled this First Day Of March 1977 [SEAL] A nest:

RUTH C. MASON C. MARSHALL DANN A I R 01TH (mnmissr'oner ufPurenIs and Trademark-8' 

1. In combination with a knitting machine having a plurality of knitting needles arranged around the periphery of said machine and adapted to move in a peripheral path about the machine frame during the knitting operation with means at a predetermined location in said path for projecting said needles to expose the hooked end thereof as they move in sequence past said location, a first oscillating circuit having a frequency determining tuned circuit for producing oscillatory energy at the oscillating frequency, a test coil at said location coupled to said tuned circuit for producing an inductive field at said oscillating frequency through which a plurality of said needles sequentially moves as they are projected at said location to enter, be exposed to and exit the field of said test coil during operation of said machine, a second oscillating circuit nominally operating at substantially the same frequency as said first oscillating circuit, a coupling for bidirectional transfer of oscillatory energy between said first and second oscillating circuits, said coupling maintaining said oscillating circuits in frequency step, means for setting a nominal phase relation between the oscillations of said first and second oscillating circuits when said plurality of needles of normal configuration are in said field of said test coil for producing a control signal having a first value which changes in response to changes in said nominal phase relation, and means responsive to predetermined change in said control signal resulting from the phase change produced by one of said plurality of needles having an inductance altering abnormal configuration in said field of said test coil for stopping operation of said machine.
 2. Detection apparatus as recited in claim 1, wherein the test coil is in the form of an elongated loop having a slot-like center opening into which the needles pass.
 3. Detection apparatus as recited in claim 2, wherein the needles normally pass in a row around the machine frame, but extend from the row at a certain location to form a protruding envelope, the test coil being mounted at the said location, so that the envelope resides in the center opening of the test coil.
 4. Apparatus according to claim 1 and including signal controlled capacitance circuit means interconnecting said oscillating circuits, an automatic phase control signal circuit responsive to detected phase difference between said oscillating circuits to produce an automatic phase control signal and means for coupling said automatic phase control signal to said signal controlled capacitAnce means to control said first and second oscillating circuits.
 5. Apparatus according to claim 4 including switch means for selectively applying said phase control signal.
 6. The method of controlling a knitting machine to stop operation upon detection of a broken needle occurring in a uniform sequence of needles comprising the steps of, operating two similar oscillators tuned to approximately the same frequency with the frequency determining elements of one of said oscillators influenced by a predetermined pattern of a plurality of knitting needles as they normally appear during operation of said machine, moving all of the needles of the machine through said pattern in sequence relative to said frequency determining elements, coupling oscillatory energy between said oscillators to lock them in frequency step with predetermined phase for said predetermined pattern, detecting the phase between said oscillators to respond to on broken needle in said pattern, and controlling operation of said machine to stop upon detection of one broken needle in said pattern. 